In the NHP CSF, 983 proteins were identified by at least two unique peptides (Fig. 1b), including proteins with key roles in neurological diseases, such as APP, TREM2 and ApoE in AD [6], DJ-1/PARK7 in Parkinson’s disease [62] and the prion protein in prion diseases [63]. The gene discussed is APOE; the disease is Parkinson disease.